AAT
Normal plasma concentration of alpha-1 antitrypsin (AAT) ranges from 1.3 to 3.5 mg/ml. Under certain conditions, AAT easily diffuses into tissue spaces and forms a 1:1 complex with target proteases, principally neutrophil elastase. Other enzymes such as trypsin, chymotrypsin, cathepsin G, plasmin, thrombin, tissue kallikrein, and factor Xa can also serve as substrates. The enzyme/inhibitor complex is then removed from circulation by binding to serpin-enzyme complex (SEC) receptor and catabolized by the liver and spleen.
Radiation Therapy
Radiation therapy, radiation oncology, or radiotherapy, can be used as part of cancer treatment to control malignant cells by a health professional. Radiotherapy may be used for curative or an ameliorating treatment. It can be used at times when a cure is not possible and the aim is for local disease control or symptomatic relief or as therapeutic treatment where the therapy has survival benefit and it can be curative. Total body irradiation (TBI) can be used to prepare a subject to receive a bone marrow transplant. Radiotherapy has other applications in non-malignant conditions, such as the treatment of trigeminal neuralgia, severe thyroid eye disease, pterygium, pigmented villonodular synovitis, prevention of keloid scar growth, and prevention of heterotopic ossification. Use of radiotherapy in these conditions is limited partly by concerns about the risk of radiation-induced cancers.
Radiotherapy can also be used in combination therapies with surgery, chemotherapy, hormone therapy, immunotherapy or combinations of therapies. Most cancer types can be treated with radiotherapy in some manner. The precise treatment intent can depend on the tumor type, location, and stage, as well as the general health of the patient.
Radiation Induced Cellular Damage
At high doses, radiation-induced cellular damage and lethality can be associated with hematopoietic and gastrointestinal radiation syndromes. Hematopoietic syndrome is characterized by loss of hematopoietic cells and their progenitors making it impossible to regenerate blood and lymphoid system. Death can often occur as a consequence of infection, hemorrhage and/or anemia. GI syndrome is caused by massive cell death in the intestinal epithelium, predominantly in the small intestine, followed by disintegration of intestinal wall and death from bacteriemia and sepsis. Hematopoietic syndrome usually prevails at the lower doses of radiation and leads to a more delayed death than GI syndrome.